Photographic reproducing apparatus



March 21, 1967 Filed-March 2, 1965 United States Patent 2 Claims. (or. 88-24) This invention relates to a photographic reproducing apparatus including a simple arrangement adapted to feed automatically sheets of photosensitive paper of a predetermined size, which sheets are brought in succession into the plane of image formation of the objective and held during exposure under perfectly flat conditions after which they are removed.

The improved reproducing apparatus includes means feeding photosensitive sheets into the focal plane and ensuring their subsequent removal, said means including an endless conveying strip trained around a driving roller and a transmission roller preferably in a stretched condition and made of a material adapted to retain charges of static electricity, said conveying strip being associated with further means adapted to transmit electric charges thereto so that, as well known per se, electrostatic attraction may hold the sheets on the strip surface facing the objective.

When the conveying strip is thus laden with static electricity, it is sufficient to place thereon a sheet of paper and to actuate the driving roller to advance said sheet which remains firmly attached to the strip by reason of the attraction provided by static electricity. Thus, without any other securing means the sheet is firmly immobilized with respect to the conveying strip and is adapted to travel in this condition regardless of the inclination of the conveying strip.

According to a further feature of the invention, there is provided substantially in the plane of image formation a stationary carrier plate made of a material adapted to receive and retain electrostatic charges suflicient for bolding the strip in contact with the plate. This arrangement ensures that both the strip and the photosensitive sheet remains in a perfectly flat condition during exposure.

The invention will be better understood from the ensuing detailed s ecification of a preferred embodiment taken in conjunction with the drawing wherein:

FIGS. 1 and 2 are diagrammatic sectional elevational views of subsequent stages of operation of an apparatus in accordance wit-h the invention.

Turning now to the figures, there is provided a supply roll, of photosensitive paper 2 engaged permanently between the driving rollers 3 and 4. The actual conveying means include an endless conveying strip 9 made of a yielding plastic material such as plasticised polyvinyl chloride adapted to receive and retain electrostatic charges. It is held in a stretched condition between a driving roller 8 associated with a roller 7 and a transmission roller 6. A roller 5 is arranged in registry with the roller 6 and cooperates with the strip 9 so as to ensure the tensioning of the end of the strip of paper laid over the conveyor strip. A cut-ting tool is provided between the pairs of rollers, 3, 4 and 5, 6, respectively, so as to cut off the desired length of paper from the continuous sheet 2 the free end of which is permanently engaged between the rollers 3 and 4.

Between the upper operative flight 9a and the lower return flight 9b of the conveying strip 9, there is inserted in contact with the lower or back face of flight 9a a stationary plate 10 made of a plastic material (e.g. nonplasticized polyvinyl chloride) adapted when subjected to friction by the strip 9 to produce a charge of static electricity.

3,309,960 Patented Mar. 21, 1967 "Ice The driving rollers 4 and 8 are rotated both at the same speed by corresponding driving means (not shown) controlled each by a cam closing a switch (neither shown) during a predetermined period. The cam may be adjusted in a known manner in accordance with the desired length of paper to be used for print.

Such arrangements may be used advantageously in photoprinting machines, adapted to reproduce documents of different sizes; the document such as that illustrated at 15 is exposed in front of an objective 12 over a glass plate 13 and is properly positioned thereon by the reglet 14 so that the edge 16 of the document 15 engaging the latter may be projected at 16a onto the edge 10a of the plate 10. Thus, the length of paper conveyed onto the plate 10 should be substantially equal to the length of the image of the document 15. In other words, the rear edge 18a of the cut off section of sheet of paper 18 should be substantially in registry with the image 17a of the edge 17 of the document opposed to the edge 16.

The operation of the described embodiment is as follows:

The controlling cams being previously adjusted in a manner depending on the length of the document 15 positioned by the reglet 14, the driving means is started, and the driving rollers 4 and 8 begin rotating. The free end 1a of the strip 2 cut off by the cutting tool 20 during the preceeding operative stage (FIG. 2) is driven forwardly between the rollers 3 and 4 and engages the clearance between the roller 5 and the endless conveying strip 9 progressing under the action of the driving roller 8.

The lower or back face of flight 9a of the conveying strip 9 engages frictionally the plate 10 and is loaded thus with static electricity. This charge exerts an attraction on the strip of paper so that the latter is held intimately in contact with the upper or front face of flight 9a which is in its turn held in a perfectly flat condition by the plate 10 which subjects it similarly to an electrostatic attraction.

The control system for the cutting mechanism of the apparatus is designed in a manner well known per se. The control cam associated with the driving roller 4 causes the latter to stop and, at the same time, operates the cutting tool 20' when the desired length of paper has passed in front of the latter. The sheet 2 unwinding from supply roll 1 is thus stopped instantaneously while a sheet of paper 18, cut off the continuous sheet 2 by the cutting tool, continues progressing between the rollers 5 and 6 and then onto the conveying strip 9 on which it is held in a flat condition, as disclosed hereinabove.

The cam controlling the rotation of the driving roller 8 is designed in a manner such as to stop the latter when the end 18b of said sheet of paper reaches a position registering with the end of the plate 10 on which is formed the image of the extreme edge of the glass plate 13 defined by the reglet 14. The photosensitive paper sheet 18 is thus ready to receive the image of the document 15.

It should be again noted that, during said operation, the sheet of paper 18 has been conveyed in an accurate manner without any possibility of a relative sliding with reference to the flight 9a of the conveying strip 9 by reason of the electrostatic adherence produced and furthermore said conveying strip and consequently the sheet of paper 18 remain perfectly flat in the plane of image formation of the objective 12 by reason of the same phenomenon which holds the strip 9 in intimate contact with the electrostatic plate 10.

It is considered to be within the scope of the invention to generate an electrostatic attraction between plate 10 and the back face of flight 9a on one hand and between the front face of flight 9a and the photosensitive sheet 18 on the other hand, by means other than the above described frictional engagement between stationary plate 10 and flight 9a.

What I claim is:

1. In a photographic reproducing apparatus of the type including an objective projecting an image of the matter to be reproduced, comprising an endless conveying strip adapted to retain electrostatic charges and having one flight extending substantially in the plane of image formation of said objective, said flight having a front face confronting said objective and a back face, said strip adapted to carry on said front face a photosensitive sheet into the area where said image is formed, means for temporarily affixing said sheet to said strip by electrostatic attraction, a stationary carrier plate, one face of which extending parallel and immediately adjacent said back face, said plate adapted to receive and retain electrostatic charges, means to electrostatically charge said plate and said strip to cause adherence by electrostatic attraction between said plate and said back face of said flight on one hand and between said front face of said flight and said photosensitive sheet on the other hand, said adherence taking place at least in the area where said image is formed.

2. A photographic reproducing apparatus as defined in claim 1, wherein said electrostatic attraction is generated by a frictional engagement between said stationary plate and said conveyor strip.

References Cited by the Examiner UNITED STATES PATENTS 11/1951 Koole et al 226-94 X 1/1965 Francis et al 8824 X 

1. IN A PHOTOGRAPHIC REPRODUCING APPARATUS OF THE TYPE INCLUDING AN OBJECTIVE PROJECTING AN IMAGE OF THE MATTER TO BE REPRODUCED, COMPRISING AN ENDLESS CONVEYING STRIP ADAPTED TO RETAIN ELECTROSTATIC CHARGES AND HAVING ONE FLIGHT EXTENDING SUBSTANTIALLY IN THE PLANE OF IMAGE FORMATION OF SAID OBJECTIVE, SAID FLIGHTS HAVING A FRONT FACE CONFRONTING SAID OBJECTIVE AND A BACK FACE, SAID STRIP ADAPTED TO CARRY ON SAID FRONT FACE A PHOTOSENSITIVE SHEET INTO THE AREA WHERE SAID IMAGE IS FORMED, MEANS FOR TEMPORARILY AFFIXING SAID SHEET TO SAID STRIP BY ELECTROSTATIC ATTRACTION, A STATIONARY CARRIER PLATE, ONE FACE OF WHICH EXTENDING PARALLEL AND IMMEDIATELY ADJACENT SAID BACK FACE, SAID PLATE ADAPTED TO RECEIVE AND RETAIN ELECTROSTATIC CHARGES, MEANS TO ELECTROSTATICALLY CHARGE SAID PLATE AND 